The Peripheral Component Interconnect (PCI) specification, including the PCI-X Addendum, is a computer industry standard specification for the connection and operation of PCI-compatible computer cards, card slots and slot circuitry in a computer. The PCI-X specification began with a first version known as the PCI-X Addendum to the PCI Local Bus Specification Revision 1.0 (referred to herein as “the PCI-X 1.0 specification”) and has evolved to a second version known as the PCI-X Addendum to the PCI Local Bus Specification Revision 2.0 (referred to herein as “the PCI-X 2.0 specification”). Among other changes, the PCI-X 2.0 specification introduced faster clocking rates (e.g. 266 MHz, 533 MHz, etc) and a lower signaling voltage (e.g. VI/O=1.5v) than that described in the PCI-X 1.0 specification (e.g. 66 MHz and 133 MHz clocking rates and VI/O=3.3v). The VI/O powers buffers that drive the high data rate signals between the card and the rest of the computer. The cards and slot circuitry that operate under the PCI-X 1.0 specification are referred to as “mode 1” devices. Similarly, the cards and slot circuitry that operate under the PCI-X 2.0 specification are referred to as “mode 2” devices. The PCI-X 2.0 specification also requires that all mode 2 cards and slot circuitry be backwardly compatible with mode 1 cards and slot circuitry. In other words, the mode 2 slot circuitry must be able to work with mode 1 cards inserted into the card slots, and the mode 2 cards must be able to work with mode 1 slot circuitry and card slots.
When a computer has both a mode 2 slot circuitry and a mode 2 card, but cannot operate in mode 2 (e.g. when the 1.5v VI/O is not properly generated), the computer nevertheless attempts to initialize the slot circuitry and card in mode 2. Afterwards, it is determined that the 1.5v VI/O has not been properly generated, so the slot circuitry and card are placed and held in reset. Thus, the slot circuitry is not operational and the card is not available to the computer. This situation may occur even though the card and slot circuitry could both potentially operate in mode 1. Additionally, this situation is highly undesirable in some applications wherein it is very important that the computer be operational, such as for a mission-critical database server or a point-of-sale server, among others.